With increase in the number of incidents of crime and in the intensity of the crimes, the recent years have seen an increasing demand for a video monitoring system using an image pickup device such as surveillance camera, the system serving as a safeguard against crimes. The image pickup devices such as the surveillance cameras have broad utility and hence, surveillance camera systems which include the image pickup devices installed at multiple locations and manage the images captured at the plural locations are spreading. Such surveillance camera systems are operated at various locations such as shopping streets, airports, harbors, and power plants.
On the other hand, since the image pickup devices have become less expensive and easier to install, the image pickup devices are installed at an increasing number of locations. However, a heavier load than ever is imposed on a user responsible for operating the monitoring system for simultaneously monitoring the images captured at the multiple locations. With the purpose of reducing the load on the user responsible for the monitoring operation, there have been developed specific person detection for automatically identifying a person by processing images of the person captured by the surveillance cameras, an image searching technique for searching out the specific person from the images captured and recorded by the surveillance camera, and the like.
Now, referring to FIG. 9, description is made on the structures of devices and processors of a conventional person detection system. FIG. 9 is a block diagram showing a structure of the conventional person detection system. A reference numeral 900 represents a network, reference numerals 901-1 to 901-n represent image pickup devices, a reference numeral 902 represents a monitor terminal, and a reference numeral 903 represents a specified person detection server. In the monitor terminal 902, a reference numeral 921 represents an image display unit, and a reference numeral 922 represents a detected object indicator. In the specified person detection server 903, a reference numeral 931 represents a pre-register and a reference numeral 932 represents a specified person detector. A character ‘n’ represents a natural number.
A specified person detection system includes the image pickup devices 901-1 to 901-n, the monitor terminal 902, and the specified person detection sever 903 which are connected via the network 900.
The image pickup devices 901-1 to 901-n are imaging devices such as network cameras. The monitor terminal 902 is a an apparatus such as a PC (Personal Computer) which includes a display monitor such as liquid crystal display or CRT, a user input device such as keyboard and mouse, and the like. The network 900 is a communication network such as leased circuit interconnecting individual devices for data communications, intranet, Internet, wireless LAN (Local Area Network) or the like.
In FIG. 9, the image pickup devices 901-1 to 901-n convert the captured images to digital data and output the resultant image data to the monitor terminal 902 and the specified person detection server 903 via the network 900.
The monitor terminal 902 includes the image display unit 921 and the detected object indicator 922. The monitor terminal serves as a user interface which displays the images inputted from the image pickup devices 901-1 to 901-n via the network 900 or messages and the like based on detection signals inputted from the specified person detection server 903 via the network 900.
The image display unit 921 processes the images inputted from the image pickup devices 901-1 to 901-n via the network 900 and displays the resultant images on a display screen of an unillustrated display monitor of the monitor terminal 902.
The detected object indicator 922 responds to the detection signal inputted from the specified person detection server 903 via the network 900 and displays a message indicating the detection of the specified person on the display screen of the display monitor. Further, the detected object indicator 922 outputs an alarm sound indicating the detection of the specified person by means of an unillustrated speaker or the like, thus informing the user of the detection of the specified person.
The specified person detection server 903 includes the pre-register 931 and the specified person detector 932. The specified person detection server 903 is an apparatus such as a computer which includes: a control and operation part such as CPU (Central Processing Unit) or MPU (Micro-Processing Unit, Micro-computer); an internal memory such as RAM (Random Access Memory) or flash memory; and a storage medium such as HDD (Hard Disk Drive).
The pre-register 931 previously registers a face image of a person to be specified. This face image is an image as a collation object image previously prepared and is inputted to the pre-register 931. The face image may be inputted by any of methods of designating a file to save the face image, routing through the image pickup device 901-1 to 901-n, using a digital camera or scanner, and the like.
The pre-register 931 performs an operation of extracting an image feature quantity from the input face image and registering the image feature quantity on a specified person list. The image feature quantity includes: color distribution of the image, distribution of edge pattern composition and the like or combinations thereof, for example. The specified person list is, for example, a database on which information pieces including the name, professional affiliation and the like of the person can be registered in addition to the image feature quantity. The specified person list is stored in the storage medium such as HDD.
The specified person detector 932 performs an operation of searching out a given person from the images inputted from the image pickup devices 901-1 to 901-n via the network 900 and then determining whether or not the searched person is the above-described person to be specified.
Disclosed in a patent literature 1 is a technique in which the feature quantity is extracted from the captured image, whether the feature quantity meets a predetermined condition or not is determined, and the image the feature quantity of which meets the condition is displayed.